Paper feeding apparatus, image forming apparatus, and paper feeding method

ABSTRACT

A paper feeding apparatus according to an embodiment includes: a pick-up roller that picks up stacked sheets; a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the stacked sheets; and an elevation control unit that elevates the stopper guide by interlocking with elevation of the pick-up roller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from: U.S. provisional application 61/354542, filed on Jun. 14, 2010; the entire contents all of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a technique of a paper feeding mechanism of an image forming apparatus.

BACKGROUND

In a paper feeding mechanism having a separation roller and an independent pick-up roller, such as a paper feeding mechanism of a manual tray or a paper feeding mechanism of an automatic document feeder of an image forming apparatus, a plurality of sheets are stacked as a bundle. However, the stack height varies depending on the number of sheets or the thickness of the sheets.

In addition, when a paper feeding operation is performed by the image forming apparatus and a sheet is transported to a paper feeding roller and the separation roller by the pick-up roller, a multiple-feed margin of the pick-up roller becomes unfavorable as the number of stacked sheets is increased.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an example of a configuration of an image forming apparatus.

FIG. 2A is a diagram showing an example in which there are a large number of sheets stacked on a tray of a paper feeding unit according to an embodiment.

FIG. 2B is a diagram showing an example in which there are a small number of sheets stacked on the tray of the paper feeding unit according to the embodiment.

FIGS. 3A and 3B are perspective views illustrating the paper feeding unit according to the embodiment in detail.

FIG. 4A is a diagram for explaining an operation of an interlocking control unit by focusing on an operation of a stopper guide (a low position of an elevation pin).

FIG. 4B is a diagram for explaining the operation of the interlocking control unit by focusing on the operation of the stopper guide (a high position of the elevation pin).

FIG. 5A is a diagram for explaining the operation of the interlocking control unit by focusing on an operation of a pick-up roller (the low position of the elevation pin).

FIG. 5B is a diagram for explaining the operation of the interlocking control unit by focusing on the operation of the pick-up roller (the high position of the elevation pin).

DETAILED DESCRIPTION

A paper feeding apparatus according to an embodiment includes: a pick-up roller that picks up stacked sheets; a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the stacked sheets; and an elevation control unit that elevates the stopper guide by interlocking with elevation of the pick-up roller.

The following description is a description of an image forming apparatus that performs color printing and may also be applied to an image forming apparatus that performs only monochrome printing.

FIG. 1 is a longitudinal cross-sectional view showing a simplified configuration of an image forming apparatus (MFP (Multi Function Peripheral)) according to this embodiment. As shown in FIG. 1, an image forming apparatus 100 according to this embodiment includes a reading section R and an image forming section P.

The reading section R has a function of scanning and reading images of a sheet original document and a book original document. The reading section R has a scanning optical system 110 including a plurality of reflective mirrors and an imaging device, and has an automatic document feeder (ADF) 109 which is a paper feeding apparatus capable of automatically transporting an original document to a predetermined place. Images of the original document that is placed on an original document tray Rt and is automatically transported by the automatic document feeder 109 or of an original document placed on a platen (not shown) are read by the scanning optical system 110.

The image forming section P has a function of forming a developer image on a sheet on the basis of the image read from the original document by the reading section R, image data transmitted to the image forming apparatus 100 from an external device, or the like. In addition, the image forming section P includes photoconductors 102Y to 102K, developing rollers 103Y to 103K, mixers 104Y to 104K, an intermediate transfer belt 106, a fixing device 107, and a discharge tray 108.

A manual paper feeding mechanism 1 (paper feeding apparatus) has a tray 141, a pick-up roller 151, a paper feeding roller 161, and a separation roller 171.

The tray 141 is a tray on which a single or a plurality of sheets are stacked, and the pick-up roller 151 picks up the sheets placed on the tray 141. The picked-up sheets are separated by the paper feeding roller 161 and the separation roller 171 sheet by sheet. The detailed configuration of the manual paper feeding mechanism 1 will be described later.

In addition, the image forming apparatus 100 includes a processor 801 which is an arithmetic processing device (for example, a CPU (Central Processing Unit)) or an MPU (Micro Processing Unit), and a memory 802 which is configured as a volatile storage device and a non-volatile storage device. The processor 801 has a function of performing various processes in the image forming apparatus 100, and a function of realizing various functions by loading programs stored in a non-volatile storage area of the memory 802 on a volatile storage area of the memory 802 and executing the loaded programs. The memory 802 may be configured from, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a DRAM (Dynamic Random Access Memory), an SRAM (Static Random Access Memory), a VRAM (Video RAM), or a hard disk drive, and has a function of storing various kinds of information and programs used in the image forming apparatus 100.

The image forming apparatus 100 has a control panel 810 having a touch panel display 806. The control panel 810 receives an instruction from a user and displays processed contents for the user.

Hereinafter, as an example of the process of the image forming apparatus 100 according to this embodiment, the overview of a copying process will be described.

First, sheets picked up from the tray 141 by the pick-up roller 151 are separated by the paper feeding roller 161 and the separation roller 171 sheet by sheet and are supplied to a sheet transport path. The sheets supplied to the sheet transport path are transported to a predetermined transport direction by a plurality of pairs of rollers.

In addition, images of a plurality of sheet original documents that are sequentially and automatically transported by the automatic document feeder 109 are read by the scanning optical system 110.

Next, image processing is performed by an image processing section including the processor 801 and the memory 802 on image data read from the original document by the reading section R. On the basis of the data after the image processing, electrostatic latent images are formed on photoconductive surfaces of the photoconductors 102Y, 102M, 102C, and 102K for transferring Y (yellow), M (magenta), C (cyan), and K (black) developer images.

Subsequently, developers agitated by the mixers 104Y to 104K in developing devices are supplied to the photoconductors 102Y to 102K on which the electrostatic latent images are formed as described above by the developing rollers (so-called, magnetic rollers) 103Y to 103K. Accordingly, the electrostatic latent images formed on the photoconductive surfaces of the photoconductors are developed.

The developer images formed on the photoconductors as such are transferred on a belt surface of the intermediate transfer belt 106 (so-called, primary transfer), and the developer images transported by the rotation of the intermediate transfer belt 106 are transferred onto transported sheets at a predetermined secondary transfer position T.

The developer images transferred onto the sheet are heated and fixed onto the sheet by the fixing device 107. The sheets onto which the developer images are heated and fixed are transported in the transport path by a plurality of pairs of transport rollers and are sequentially discharged to the discharge tray 108.

Next, the configuration of the manual paper feeding mechanism 1 is described with reference to FIGS. 2A to 5B. In addition, the following description is a description of the manual paper feeding mechanism 1 and can also be applied to the automatic document feeder 109 which is another paper feeding apparatus.

First, the configuration and operation of the manual paper feeding mechanism 1 will be described with reference to FIGS. 2A and 2B. In addition, a solid arrow in FIGS. 2A and 2B represents a rotation direction of the pick-up roller 151, and dashed arrows represent a transport direction of the sheet when the pick-up roller 151 rotates in the solid arrow direction (in the same manner in the following figures).

The manual paper feeding mechanism 1 includes a pick-up arm 15 that supports the pick-up roller 151 in addition to the tray 141, the pick-up roller 151, the paper feeding roller 161, and the separation roller 171 described above. The pick-up arm 15 rotates about a shaft 13 (described later) which is substantially the same shaft as a rotation shaft of the paper feeding roller 161.

In addition, the manual paper feeding mechanism 1 elevates in the same direction of a z axis while interlocking with the elevation of the pick-up roller 151 in the z axis, and has a stopper guide 2 which restricts the number of sheets picked up by the pick-up roller 151 to be equal to or smaller than a predetermined number (for example, to be 5 to 10 or less). A side wall of the stopper guide 2 on the sheet side is adjusted to abut on front end portions of the sheets at a lower portion of a sheet bundle S1 in the z-axis direction and so as not to abut on the front end portions of the sheets at an upper portion in the z-axis direction. In addition, the side wall that abuts on the sheets is provided with a gradient such that a lower side of the side wall further deviates to a stack side of the sheets than an upper side thereof, as apparently shown in FIGS. 2A and 2B.

When there are a large number of sheets stacked, as shown in FIG. 2A, the pick-up roller 151 is at a high position in the z-axis direction by the height of the sheet bundle S1. Interlocking with the high state, the stopper guide 2 is at a high position. On the other hand, when there are a small number of stacked sheets, as shown in FIG. 2B, the pick-up roller 151 is at a lower position in the z-axis direction by the height of the sheet bundle S1, and the stopper guide 2 is also at a low position by interlocking with the pick-up roller 151.

As the stopper guide 2 moved by interlocking with the elevation of the pick-up roller 151 is provided, the pick-up roller 151 may transport only sheets at a higher position in the z-axis direction than that of a top surface of the stopper guide 2 as sheets to be transported. Therefore, even when a large number of sheets are stacked, the multiple-feed margin of the pick-up roller 151 is restricted to several numbers of sheets (that is, the number of sheets that are higher than the top surface of the stopper guide 2).

The stopper guide 2 is controlled and adjusted so that a height obtained by subtracting the height of the top surface of the stopper guide 2 from the stack height of the sheets (a height H in FIGS. 2A and 2B) is in a predetermined range (a range of, for example, the thickness of about 5 to 10 sheets used although depending on the precision of the apparatus). In addition, it is preferable that the height H be controlled and adjusted to be the thickness of a single sheet (in this embodiment, about 0.3 mm although depending on the type of a sheet).

Next, an interlocking method of the pick-up roller 151 and the stopper guide 2 will be described with reference to FIGS. 3A to 5B.

FIGS. 3A and 3B are perspective views of the manual paper feeding mechanism 1 viewed from obliquely above from different view points. FIGS. 4A and 4B are schematic views focusing on an operation of the stopper guide 2 when viewed from the view point direction shown in FIG. 3A. FIGS. 5A and 5B are schematic views focusing on an operation of the pick-up roller 151 when viewed from the view point direction shown in FIG. 3B.

The manual paper feeding mechanism 1 includes an interlocking control unit 30 as a mechanism for interlocking the elevations of the pick-up roller 151 and the stopper guide 2 with each other. The interlocking control unit 30 includes a lever 11, an elevation solenoid 12, an elevation pin 12A (a portion) (see FIGS. 4A to 5B), the shaft 13, a roller elevation lever 14, and the pick-up arm 15.

The elevation solenoid 12 is a solenoid for lifting and lowering the elevation pin 12A in a height direction (the z-axis direction). In addition, one end of the lever 11 abuts on a front end portion of the elevation pin 12A, and the roller elevation lever 14 abuts on an upper portion of the one end of the lever 11 (see FIGS. 4A to 5B). Of course, a vertical order of the lever 11 and the roller elevation lever 14 is not limited to this example. In addition, in the following description, it is described that a relative position of the front end portion of the elevation pin 12A, the one end of the lever 11, and the roller elevation lever 14 is fixed.

First, elevation control of the stopper guide 2 by the interlocking control unit 30 will be described with reference to FIGS. 4A and 4B. First, as the elevation solenoid 12 receives a DC current or a pulse signal, the elevation solenoid 12 moves the front end portion of the elevation pin 12A from a lower position (FIG. 4A) to an upper position (FIG. 4B). As the front end portion of the elevation pin 12A is moved upward, the one end of the lever 11 and the roller elevation lever 14 can be pushed up. When the elevation pin 12A is moved downward from above, similarly, the one end of the lever 11 and the roller elevation lever 14 are also moved downward.

Though the one end of the lever 11 abuts on the front end portion of the elevation pin 12A as described above, the other end of the lever 11 is a spherical body, and the spherical body is fitted into the stopper guide 2. In addition, the lever 11 rotates about a lever fulcrum 11A. Since the lever 11 has this configuration, the one end of the lever 11 is moved upward as being pushed up by the elevation pin 12A, and the other end thereof is moved downward, so that the stopper guide 2 is also moved downward. That is, the state of FIG. 4A becomes the state of FIG. 4B. On the contrary, when the front end portion of the elevation pin 12A is moved downward, the other end of the lever 11 is moved upward, and the stopper guide 2 is also moved upward. That is, the state of FIG. 4B becomes the state of FIG. 4A.

Next, elevation control of the pick-up roller 151 by the interlocking control unit 30 will be described with reference to FIGS. 5A and 5B. The front end portion of the elevation pin 12A is moved from the lower position (FIG. 5A) to the upper position (FIG. 5B) by the control of the elevation solenoid 12 (control for transiting the state of FIG. 4A to the state of FIG. 4B described above). As the front end portion of the elevation pin 12A is moved upward, the one end of the lever 11 and the roller elevation lever 14 can be pushed up. When the elevation pin 12A is moved downward from above, similarly, the one end of the lever 11 and the roller elevation lever 14 are also moved downward.

Since the roller elevation lever 14, the shaft 13, and the pick-up arm 15 are formed integrally, when the roller elevation lever 14 is pushed up by the elevation pin 12A, the pick-up arm 15 is moved downward with respect to the shaft 13. When the pick-up arm 15 is moved downward, the pick-up roller 151 provided at the front end of the pick-up arm 15 is also moved downward. That is, the state of FIG. 5A becomes the state of FIG. 5B. On the contrary, when the front end portion of the elevation pin 12A is moved downward, the pick-up arm 15 and the pick-up roller 151 are moved upward. That is, the state of FIG. 5B becomes the state of FIG. 5A.

As such, as the elevation solenoid 12 moves the elevation pin 12A in the vertical direction, the stopper guide 2 and the pick-up roller 151 are moved in the same direction. That is, when the pick-up roller 151 is moved upward, the stopper guide 2 is also moved upward, and when the pick-up roller 151 is moved downward, the stopper guide 2 is also moved downward. In addition, a configuration in which the pick-up roller 151 and the stopper guide 2 are moved in different directions from each other can also be applied as the embodiment. For example, when the stopper guide 2 is caused to directly abut on the elevation pin 12A without the use of the lever 11, the configuration in which the pick-up roller 151 and the stopper guide 2 are moved in vertically opposite directions to each other is implemented.

In addition, movement distances of the stopper guide 2 and the pick-up roller 151 in the vertical direction and a relative movement distance ratio of the stopper guide 2 and the pick-up roller 151 are adjusted by a position of the shaft 13 or a shaft of the lever fulcrum 11A, arm lengths or an arm length ratio of the roller elevation lever 14, the pick-up arm 15, and the lever 11.

In addition, a unit that moves the pick-up roller 151 upward or downward, that is, a unit configured by the elevation solenoid 12, the elevation pin 12A, the shaft 13, the roller elevation lever 14, and the pick-up arm 15 may use an existing unit, the interlocking control unit 30 may also be configured by including the lever 11, the lever fulcrum 11A, and the stopper guide 2 in the existing unit.

Although electrical power is described as a driving force of the elevation solenoid 12, a spring force (elastic force) may also be used, and a combination of electrical power and elastic force that is used for returning a shape to its original state may be used.

The technique described according to the embodiment may be applied to any mechanism that feeds sheets.

As described above in detail, according to the technique described in the specification, a level at which the front end portion of the sheet is inserted between the paper feeding roller and the separation roller is in a predetermined range, so that a stable multiple-feed margin can be ensured regardless of the number of stacked sheets.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of invention. Indeed, the novel apparatus and methods described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the apparatus and methods described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. 

1. A paper feeding apparatus comprising: a pick-up roller that picks up stacked sheets; a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the stacked sheets; and an elevation control unit that elevates the stopper guide by interlocking with elevation of the pick-up roller.
 2. The apparatus according to claim 1, wherein the elevation control unit elevates the stopper guide so that a difference between a stack height of the sheets and a height of a top surface of the stopper guide is in a predetermined range.
 3. The apparatus according to claim 1, wherein the elevation control unit elevates the stopper guide so that the number of sheets picked up by the pick-up roller is equal to or smaller than a predetermined number.
 4. The apparatus according to claim 1, wherein the elevation control unit includes: a pick-up arm that supports the pick-up roller; an elevation solenoid that controls elevation of a portion that pushes the pick-up arm up or moves the pick-up arm down; and a lever of which one end abuts on the portion elevated by the elevation solenoid, and of which the other end includes the stopper guide, so as to rotate about a predetermined fulcrum.
 5. The apparatus according to claim 4, wherein the pick-up roller is lowered when the portion is moved upward, and is lifted when the portion is moved downward.
 6. The apparatus according to claim 1, wherein the elevation control unit moves the stopper guide upward when the pick-up roller is moved upward, and moves the stopper guide downward when the pick-up roller is moved downward.
 7. The apparatus according to claim 1, wherein the side wall of the stopper guide that abuts on the sheets is provided with a gradient such that a lower side of the side wall further deviates to a stack side of the sheets than an upper side thereof.
 8. An image forming apparatus comprising: an image forming section that forms an image on a sheet; a tray on which the sheets are stacked; a pick-up roller that picks up the sheets stacked on the tray and transports the sheets to the image forming section; a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the sheets stacked on the tray; and an elevation control unit that elevates the stopper guide by interlocking with elevation of the pick-up roller.
 9. The apparatus according to claim 8, wherein the elevation control unit elevates the stopper guide so that a difference between a stack height of the sheets and a height of a top surface of the stopper guide is in a predetermined range.
 10. The apparatus according to claim 8, wherein the elevation control unit elevates the stopper guide so that the number of sheets picked up by the pick-up roller is equal to or smaller than a predetermined number.
 11. The apparatus according to claim 8, wherein the elevation control unit includes: a pick-up arm that supports the pick-up roller; an elevation solenoid that controls elevation of a portion that pushes the pick-up arm up or moves the pick-up arm down; and a lever of which one end abuts on the portion elevated by the elevation solenoid, and of which the other end includes the stopper guide, so as to rotate about a predetermined fulcrum.
 12. The apparatus according to claim 11, wherein the pick-up roller is lowered when the portion is moved upward, and is lifted when the portion is moved downward.
 13. The apparatus according to claim 8, wherein the elevation control unit moves the stopper guide upward when the pick-up roller is moved upward, and moves the stopper guide downward when the pick-up roller is moved downward.
 14. The apparatus according to claim 8, wherein the side wall of the stopper guide that abuts on the sheets is provided with a gradient such that a lower side of the side wall further deviates to a stack side of the sheets than an upper side thereof.
 15. A paper feeding method of an image forming apparatus, wherein a paper feeding apparatus of the image forming apparatus includes a pick-up roller that picks up stacked sheets, and a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the stacked sheets, the method includes elevating the stopper guide by interlocking with elevation of the pick-up roller.
 16. The method according to claim 15, wherein the paper feeding apparatus elevates the stopper guide so that a difference between a stack height of the sheets and a height of a top surface of the stopper guide is in a predetermined range.
 17. The method according to claim 15, wherein the paper feeding apparatus elevates the stopper guide so that the number of sheets picked up by the pick-up roller is equal to or smaller than a predetermined number.
 18. The method according to claim 15, wherein the paper feeding apparatus elevates the stopper guide by interlocking with elevation of the pick-up roller by using: a pick-up arm that supports the pick-up roller; an elevation solenoid that controls elevation of a portion that pushes the pick-up arm up or moves the pick-up arm down; and a lever of which one end abuts on the portion elevated by the elevation solenoid, and of which the other end includes the stopper guide, so as to rotate about a predetermined fulcrum.
 19. The method according to claim 18, wherein the pick-up roller is lowered when the portion is moved upward, and is lifted when the portion is moved downward.
 20. The method according to claim 15, wherein the side wall of the stopper guide that abuts on the sheets is provided with a gradient such that a lower side of the side wall further deviates to a stack side of the sheets than an upper side thereof. 